A mobile communication repeater is used to enable communication of a mobile communication telephone in a room where a mobile communication signal intensity is weak. The mobile communication repeater is a device which is installed in a place where a radio wave is weak or cannot reach between a base station and a terminal and supplies an excellent signal thereto to enable a stable wireless communication service.
Generally, a donor antenna installed in an outdoor location, where an electric field intensity is high, supplies a signal received from the base station to the mobile communication repeater installed in a room, and the mobile communication repeater appropriately amplifies the signal and supplies the signal to an indoor antenna (Service Antenna).
However, the donor antenna needs to be in a state facing an adjacent base station, and thus the donor antenna is installed outdoors so that its installation direction appropriately faces the adjacent base station. In a configuration of the mobile communication repeater, an antenna cable needs to be drawn into the room by penetrating through a wall surface in order to connect the donor antenna installed in the outdoor location to the indoor mobile communication repeater.
If the donor antenna is installed in the room to avoid penetration of the antenna cable through the wall surface, the direction of the donor antenna installed in the room needs to be set to an appropriate angle to face the adjacent base station.
In this case, there is a problem that irregular reflection caused by wall surfaces of the building and indoor structures makes it difficult to bring a facing state to the base station into an optimum state, and a reflected wave of the irregular reflection is fed back to another antenna, namely the service antenna, of the mobile communication repeater installed in the room and causes oscillation.
As described above, even if the donor antenna is installed in the room and a through-hole for drawing in the antenna on the wall surface of the building is not used, but if a window direction does not coincide with the direction of the base station, the base station and the antenna attached on the wall surface do not face each other. Accordingly, a radio wave from the base station does not advance in a main radiation direction of the antenna, and the donor antenna cannot serve a function of relaying signals since optimum transmission and reception of radio waves cannot be performed with the base station. Patent literature 1 discloses a repeater which includes a donor antenna and a service antenna in one casing and relays communication between a base station and a mobile station by being installed in a room.